A primal-dual approximation algorithm for partial vertex cover: making educated guesses

  • Authors:
  • Julián Mestre

  • Affiliations:
  • Department of Computer Science, University of Maryland, College Park, MD

  • Venue:
  • APPROX'05/RANDOM'05 Proceedings of the 8th international workshop on Approximation, Randomization and Combinatorial Optimization Problems, and Proceedings of the 9th international conference on Randamization and Computation: algorithms and techniques
  • Year:
  • 2005

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Abstract

We study the partial vertex cover problem, a generalization of the well-known vertex cover problem. Given a graph G=(V,E) and an integer s, the goal is to cover all but s edges, by picking a set of vertices with minimum weight. The problem is clearly NP-hard as it generalizes the vertex cover problem. We provide a primal-dual 2-approximation algorithm which runs in O(V log V + E) time. This represents an improvement in running time from the previously known fastest algorithm. Our technique can also be applied to a more general version of the problem. In the partial capacitated vertex cover problem each vertex u comes with a capacity ku and a weight wu. A solution consists of a function x: V →ℕ0 and an orientation of all but s edges, such that the number edges oriented toward any vertex u is at most xuku. The cost of the cover is given by ∑v∈Vxvwv. Our objective is to find a cover with minimum cost. We provide an algorithm with the same performance guarantee as for regular partial vertex cover. In this case no algorithm for the problem was known.